1. Field of the Invention
This invention relates to change gear transmissions and in particular to simple change gear transmissions utilizing multiple compounded countershafts and having a unique sliding tube clutch structure.
2. Description of the Prior Art
Simple transmissions, that is transmissions utilizing a one piece mainshaft, are well known in the prior art. Transmissions utilizing either simple or compound mainshafts in connection with multiple countershafts wherein either the mainshaft gears or the countershaft gears are mounted in a radially floating manner relative to the other gears are well known in the prior art. Examples of such transmissions may be seen by reference to U.S. Pat. Nos. 3,105,395; 3,255,644; 3,283,613; 3,335,616; 3,349,635; 3,378,214; 3,500,695; 3,648,546 and 3,799,002 all of which are hereby incorporated by reference.
The prior art transmissions, particularly those transmissions utilizing a floating mainshaft and/or floating mainshaft gears in connecting with multiple countershafts, have proven to be highly acceptable. However, to achieve a sufficiently large range of available gear ratios, it has generally been necessary to utilize a compound transmission. Such transmissions generally comprise a main transmission section connected in series with an auxiliary transmission section of either the "range" type or the "splitter" type or a combination thereof as is well known in the prior art. Such transmissions are highly effective and commercially successful, especially for use in heavy duty vehicles wherein a large range of ratios is required and/or a large number of individual gear ratios is required. Such heavy duty compound transmissions typically have 9, 10, 12, 13 or more forward gear ratios.
There has, however, developed a need for transmissions having a greater range of ratios and/or a greater number of ratios than is normally available in a simple countershaft simple transmission as the centerline distances and/or countershaft length required in prior art simple transmissions to provide same would become too great yet not justifying the somewhat expensive structure and controls required for a compound transmission.
To meet this need, simple transmissions utilizing compounded countershafts have been proposed. An example of such a simple transmission utilizing compounded countershafts may be seen by reference to U.S. Pat. Nos. 4,152,949 and 4,269,077 both hereby incorporated by reference. Such transmissions, while suitable for many purposes, are not totally satisfactory for certain applications as the clutch and/or idler structure required an axial dimension which might be excessive and/or prevent widening of the gear tooth faces for increased torque transmitting capacity. The prior art transmissions often were also not totally satisfactory as a standard "H" or "double H" type shift pattern was not provided and/or required a complicated lever mechanism.